The objective of the proposed project is to study prospectively (1) the effects which pregnancy has on the epileptic patient and (2) the teratogenic effect of anticonvulsant drugs. Evidence to date indicates that pregnancy may alter the pharmacokinetics and metabolism of drugs. Alterations in drug dosages are definitely necessary to maintain seizure control during pregnancy. Seizures exacerbate in more than 50% of pregnant epileptics, even when drug dosages are appropriately changed. The frequency of this change has not been accurately documented and the etiology, which may be secondary to changing hormone levels, has not been clarified. Studies on teratogenesis of anticonvulsant drugs have concentrated on the changes in the children but have not examined the mothers during pregnancy to document their metabolic or drug status. In this project, we propose to examine both the mothers during pregnancy and their offspring. The children will be reexamined periodically for 5 years. Major malformations occur in 6 to 8% of children born to mothers taking anticonvulsant drugs. Up to 30% may have dysmorphic features. Delayed maturation and development has also been reported to occur but the true incidence, severity and etiology has not been defined. In this study, we hope to elucidate some of these questions by monitoring the mothers during pregnancy and serially examining the children for neurological, developmental and morphologic abnormalities.